Vulcanization process and product



Patented Mar. 29, 1927.

I 1,622,535 UNITED STATES PATENT OFFICE.

PAUL I. MURBII L, OF PLAINFIELD, NEW JERSEY, ASSIGNOR TO B. T. 'VAINDERBILT 00., INC., 0]? NEW YORK, N. Y., A CORPORATION OF NEW YORK.

V'U'LCANIZATION PROCESS AND PRODUCT.

No Drawing.

This invention relates to the vulcanization of rubber and includes the new vulcanization process as well as the new vulcanization products.

According to the present invention, the vulcanization is carried out with the addition to the rubber of organic selenium compounds containing the group CSS-, these selenium compounds being active both as vulcanizing agents and as accelerators of vulcanization.

The new organic selenium compounds used in the process of the present invention and in making the new vulcanized products of the invention have the following general formula (CSS) Se, and they may contain nitrogen, oxygen or carbon join-ed to the carbon of the above formula. -Among the new vulcanizing agents which are particularly valuable for use in carrying out the invention are the selenium-salts or compounds of diethyland dimethyldithiocarbamic acid of the general formula (RRN.CSS),Se, Where R and R represent simple or substituted hydrocarbon radicals which may be the same or different radicals, suchas methyl, ethyl, phenyl, benzyl, etc., or where RRN represents piperidyl etc.

acids of the general formula (ROCSSLSe and from dithioacetic, dithiobenzoic, etc., acids, of the general formula (EC.CSS)S6. The new selenium compounds can be produced in accordance with the process more fully described in'my companion application Serial Number 59,571 filed of even date by the action of a soluble selenite such as sodium selenite upon the sodium salt of the dithioacid, with the addition of a mineral .or organic acid such as hydrochloric acid.

The selenium diethyland dimethyldithiocarbamates may be produced, for example, by the reaction of the sodium dimethylor diethyldithiocarbamate (4 mols.) upon sodium selenite (1 mol.) and 6 mols. of h drochloric acid. The selenium diethyldithiocarbamate is readily soluble in carbon bisulfide and crystallizes therefrom on the addition of benzol. When thus 'crystallizedit forms brilliant orange colored plates melting at about 94.-95 O. The technical product has a melting point of about 90-95 C. The corresponding dimethyl compound is a yellowish powder melting at about 163-165 C. and is so sparingly soluble 1n the usual Application filed September 30, 1925.

, canization of rubber, they .by weight of the rubber.-

Similar selenium compounds can be derived from the xanthic' Serial No. 59,573.

organic solvents that it is difiicultly obtainable in a pure crystalline form.

In using the new compounds in the vulmay be used as vulcanizing agents without the addition of sulfur or other sulfur-containing compound or they may be used as accelerators of vulcanization with the addition of sulfur. They may be compounded with the rubber mix in the usual way. When used as vulcanizing agents without the addition of sulfur they may be used, e. g., to the extent of 2 to 3% When used as accelerators, they may be used only to the extent of a small fraction of 1%, e. g., around to 4% of the rubber.

The following specific example further illustrates the invention:

The rubber compound was vulcanized using selenium diethyldithiocarbamate as vulcanizing agents in the following mixz.

Pale crepe 100 l/Vhiting 50 Zinc oxide 5 Vulcanizing agent 3 Timeaud temperature of cure gfigg 10 min. at 40 lbs. (141 C.) 2,780 lbs. 665% 20 min. at 40 lbs. (141 C. 2,5401b6. 650% 40 min. at 40 lbs. (141 C. 2,440-lbs. 6607 min. at 401m. 141 0.).. 2 mm. 6807: 120 min. at 40 lbs. (141 C.) 2,240 lbs. 680% It will be noted that the cure wascompleted in about 10 minutes,.and that the stock was not seriously overcured, in two hours, indicating a long curing ranges The following example ives the results obtained with the use of te new seleniumcompounds as accelerators 1n the following mix:

Pale crepe 100 Whiting 50 Zinc oxi de 5 Sulfur 4 The selenium dimethyl or diethyldithiocarmethyldithlocarbamate.

' Tensile Tensile Time and temperature of cure and and stretch stretch 3, 440-690 3, 340-690 3, 700-685 3, 320-665 2, 720-660 3, 520-665 10 min. at 20 lbs 3, 120-670 15 min. at 20 lbs- 19 0 3 240-635 30 min. at 20 lbs" 3, 300-730 3 120-680 5 mm. at 401bs--. 3, 040-710 3, 260-710 15 mm. at 40 lbs 3, 200-700 2830-100 30 min. at 40 lbs 2, 910-670 2, 690-670 It will be seen that the vulcanization'can be effected at ordinary temperatures and that at higher temperatures the vulcanization is completed in a short period of time and that the compounds on further curing are only slowly reduced in tensile strength and elongation.

The following example illustrates the useof the new organic selenium compounds as accelerators in a pure gum stock. The compound used was as follows:

Pale crepe 100 Zinc oxide 5 Sulfur 4 Accelerator 0, 25

Using selenium dimethyldithiocarbamate as the accelerator, the following results were obtained:

Time and temperature of cure I 4, 700-720 a, s1os2s 4, 400-780 From these examples it will be seen that the new organic selenium compounds used in the process of the present invention are rapid in their action, causing cures at low temprature and in'a short time, and that i the stocks are not injured by longer exposure to heat, i. e., do not overcure readily.

1,0aa,cea

The new vulcanized products have improved properties and are characterized by containing selenium as well as sulfur therein, together with products of reaction of the organic selenium compounds.

I claim:

1. The method of vulcanizing rubber which comprises subjectin the rubber to vulcanization with the addition thereto of an organic selenium compound containing which comprises subjecting the rubber to vulcanization in the presence of selenium diethyldithiocarbamate. I

5. The method of vulcanizing rubber which comprises subjecting the rubber to vulcanization in the presence of selenium dialkyldithiocarbamate. I

6. The method of vulcanizing rubber which comprises subjecting the rubber to vulcanization with theaddition thereto of an organic selenium compound containing the following group: CSS- as the vulcanizing agent without the addition of sulfur.

7. The method of vulcanizing rubber which comprises subjecting the rubber to vulcanization with the addition thereto of an organic selenium compound of the following general composition: Se(SSO 4 as the vulcanizing agent without the ad ition of sulfur.

8. The method of vulcanizing rubber which comprises subjecting the rubber to vulcanization with the addition thereto of an organic selenium compound of the following general formula: (RRNCSShSe, where R and R are hydrocarbon radicals, as

lit)

the vulcanizing agent without the addition i of sulfur.

9. The method of vulcanizing rubber which comprises subjecting the rubber to vulcanization in the presence of selenium diethyldithiocarbamate as the vulcanizing agent without the addition of sulfur.

10. The method of vulcanizing rubber which comprises subjecting the rubber to vulcanization in the presence of selenium dialkyldithiocarbamate as the vulcanizing agent without the addition of sulfur.

11. New vulcanized rubber products vulcanized with the addition thereto before vulcanization of anorganic selenium compound containing the following group: CSS

12. New vulcanized rubber products vulcanized with the addition thereto before 5 vulcanization of an organic selenium compound of the following general composition: Se(SSC-);.

13. New vulcanized rubber products vulcanized with the addition thereto before 1 vulcanization of an organic selenium compound of the following general formula:

(RR'NCSS) Se, where R and R? carbon radicals.

14. New vulcanized rubber products vulcanized in the presence of selenium diethyldithiocarbamate.

15. New vulcanized rubber products vulcanized in the presence of selenium dialk'yldithiocarbamate.

In testimony whereof I afiix my signature.

PAUL I. MURRILL.

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